One important requirement for high quality ink-jet printing is that there be an unvarying distance between ink-jet print head nozzles and a print surface of the strip of paper to be printed.
Prior art attempts to provide this constant distance used a fixed, flat platen. Such attempts have proved unsatisfactory when incorporated in multiple print head ink-jet printers in which a plurality of ink-jet print heads are aligned along a predefined path of a continuous strip of paper or like printable material. Consider an elongated flat platen mounted opposite to the series of ink-jet print heads, and with the paper strip fed over the platen by guide rollers or pairs of feed rollers disposed adjacent to both ends of the platen. The paper strip is prone to flutter over the platen because of the extended distance between the guide rollers or the like that is necessary to permit all of the print heads to print on the paper without roller means that lead to smudging of freshly deposited ink. This fluttering gives rise to unacceptable variations in the spacing between the printable material surface and the print heads.
U.S. Pat. No. 6,309,046, which issued to Izawa et al. on Oct. 30, 2001, teaches an ink-jet printer having a plurality of ink-jet heads for printing on a continuous strip of paper. However, Izawa et al. require a turnover station between a first and a second printing station in order to provide printing on both sides of the paper. Also, the ink-jet print heads are oriented in a plurality of directions, and ink can be smudged when passing over a roller guide.